Insurance is to protect the business -- first against damage to the business, then against damage to or from the employees (by insuring them and insuring against lawsuit from them), then against damage to or from the customers and general public (ditto, ditto). That's not a HUGELY complicated mix, but it means you need to make some active decisions about how much you consider yourself to be at risk of any of these, how much of that risk you're willing to carry yourself ("self-insuring" by raising your deductables), and so on.

If you don't trust the broker, find a broker you do trust. Yes, they're getting a percentage from the insurance companies... but a _good_ broker understands that they want you to be happy so you stay with them, and direct friends to them, rather than looking elsewhere.

If you want a sanity-check on needs and prices, you could ask other people in your general area and in the same business what their costs are like. You may not want to ask the folks you'll be in most direct competition with, but if you go out a few towns the costs should be similar and they'll have less reason to get defensive about helping you. (I don't know how collegial your industry is. In locksmithing, that depends on how under- or over-served the areas is and on the individual shop owners' attitudes.)

Certainly ask whoever is selling you the business to show you what they've been buying and how much they've been paying for it, for insurance and for everything else, before you agree to buy it.